I have an executable that looks for a particular DLL. I have changed the source for DLL and recompiled it (written and recompiled in VB6). Once I replace the DLL, the executable hits a runtime error when it gets to using that particular DLL. Works ok when I recompile the executable.
So my question is, with same DLL path, same name, and virtually identical DLLs, why does the executable need to be recompiled?
This is driving me bananas so any thoughts would be appreciated. Thanks, Callum.
A VB6 (or any COM) DLL has unique IDs for itself and its public interfaces, if you recompile these can change and any existing code bound to the old IDs fails.
Tldr; Tick "Binary Compatibility" in the DLL's project options & select the old working DLL as the thing to maintain compatibility with & recompile.
Detailed explanation: I keep hearing about DLL hell - what is this?
Related
I have a vb.net application I'm looking to be able to distribute in the near future.
I'm not the original architect and the previous developer referenced a handful of .dll's that are under a GPL license.
All of the software that includes these dll's are freely available online, so my customer can go download and install them if they need that functionality. So I don't have to distribute the DLLs.
Currently they are referenced under the "Reference" part of the project file.
My question is, how do I resolve these dll's in a way similar to how the "references" dons it, but at runtime.
My plan is to search the registry for the location of these dll's and reference that location, but given the file location of the .dll, how do I "pull" that code into my project.
Thanks
You may try this
Search for Dll on specified path for dll
Use reflection to load assembly or dll into you code at runtime
Create runtime object from the loaded dll
Call required functionality from the dll
Reflection is the key solution to your problem that you may use to plugin new functionality into your project without distributing the dlls
This is the only solution that works
http://mylifeandsql.com/2018/03/26/replication-readpast-error/
also you can just start your migration with the following command
Sql(#"SET TRANSACTION ISOLATION LEVEL READ COMMITTED");
This will replicate dll changes like adding new column to a replicated table
You will also find that the column is automatically added to replicated articles > columns
No need to create a new snapshot nor set the sync to re-initialization ☺
Thanks
I've got an old legacy application for communicating via serial port to an embedded controller communications bus. that someone else developed.
The application is written in VB6, and is structured as two projects - a DLL to handle the connection and communications logic, with an application GUI project.
I was hoping to be able to write a new application GUI (in C++ ideally) to use the existing DLL as-is, but I'm having lots of problems working out how to import it.
So I'm wondering, is it even going to be possible to use this old DLL into a C++ project as is? or is it possible to import into a C# project? or a VB.NET project? (would prefer not to use VB, but can if I have to)
Where I am now:
I have the existing compiled executable and DLL, and these run on my system.
I also have the project files, and they're all readable in notepad++ but I don't have VB6, and importing the project into visual studio VB.NET 2008 express isn't at all straightforward. Especially not without a working example to dig through and play with first (DLL project may be importable, but has 50+ things indicated as needing changing in the upgrade report. It also seems to be ignoring three .cls files that look very important to my not particularly VB6-savvy eyes... The application project has a message in the upgrade report about something "missing a design time license" and the only project files that actually seem to come into the project explorer for imported project is the project file itself, and the assembly info file.)
Most examples of how to import a DLL into VS C++ assume you have a solution with the DLL project all compiling nicely alongside your project that will use it. Or at least a .DLL and .lib and .h file... I spoke with the original developer of the code (in another city, we don't work directly) and got a .lib to match my .dll, but still have no .h file.
I'm usually fine to bash through something new, but without a baseline working example of the project even in VB6 that I can get my understanding from, it makes this very hard. Also a lack of similar questions anywher google can find them on the net makes me wonder if this is something i should be even attempting.
I'm working on getting a non-express copy of visual studio if that will make any difference (express worked fine for everything up until now so I never needed anything more) but that will take a number of weeks, most likely.
Any suggestions would be very much appreciated.
thanks for reading!
I have to disclaim this as I have no experience doing it, but merely found that it should be possible given some reading of the docs on the subject.
I'm not sure you'll have much luck with the VB to .NET import/conversion process if there is a lot of low level stuff going on. The existing dll is likely a COM object, no?
It seems like there is some MSDN documentation to get you started from C++ using COM object dlls - and it looks like the #import directive will generate some .h (header) files as well.
http://msdn.microsoft.com/en-us/library/8etzzkb6.aspx
So I would try simply adding an #import directive for it.
#import "somelibrary.dll"
and see what visual studio generates.
Have a look at the following example as well, (copied shamelessly from another forum)
#import "F:\proj\VB6\ActiveXDLL\VBTestDLL.dll"
using namespace VBTestLib;
void CDialogTestDlg::OnButton1()
{
HRESULT hresult;
CLSID clsid;
_CTest *t; // a pointer to the CTest object
_bstr_t bstrA = L"hello";
_bstr_t bstrB = L" world";
_bstr_t bstrR;
::CoInitialize(NULL);
hresult=CLSIDFromProgID(OLESTR("VBTestLib.CTest"), &clsid);
hresult= CoCreateInstance(clsid,NULL,CLSCTX_INPROC_SERVER,
__uuidof(_CTest),(LPVOID*) &t);
if(hresult == S_OK)
{
bstrR = t->vbConcat(bstrA , bstrB);
AfxMessageBox((char*)bstrR);
}
}
I disassemled a game's DLL and want to insert some code.
I need asm code to call another DLL in the current directory(I'm on Windows).
The background is, that I want to be able to execute custom code in my DLL,
but I can't load the DLL. So my idea was to load the DLL via modified game DLL.
There may be a function in the game which gives me the current directory path the DLL's are but I think I won't find it.
The calls you are looking for are LoadLibrary, which will search in a selection of places including the current directory for the DLL and then load it, then GetProcAddress.
If the DLL makes any other Win32 calls it is probably already linked against kernel32.dll, so that's all you need to do.
It is arguable as to whether modifying the DLL or using DLL injection is faster in terms of how long it takes to write the code since you're going to have to reverse engineer anyway, however, one advantage of pure DLL injection is that all existing code remains unmodified in terms of the installation, making these modifications easier to undo should the user wish to "unpatch" whatever you are doing.
Microsoft Detours comes with setdll.exe and withdll.exe, those utilities will let you start an exe with a custom dll file.
I am getting error,
ActiveX component can't create object.
Actually I have VB6 DLLs where business logic resides and I am calling that DLL function in my VB.NET application, all DLLs are dependent on other DLLs. I am getting the error from one of the DLLs
Any ideas?
Usually that error points to a COM dll that is not registered. You need to look at the chain of calls and find out which COM components you need and make sure they are available. Process Monitor (from sysinternals) may help you find it when it reads from the registry and can't find it.
Four common causes are:
1. You do not have a required TLB or ActiveX DLL/OCX file
2. A TLB or ActiveX DLL/OCX needed by the project is present but not registered on your system
3. The VB runtimes are an earlier version than the one you need to run the project
4. A required TLB or ActiveX DLL/OCX file is corrupt
Do you have access to the troublesome DLL source code?
Also check permissions. The user account that the vb.net application is running under will need permissions to be able to create the vb6 dll
Process Monitor will definately help find the missing DLL, but frequently the task can be achieved more quickly with Dependency Walker.
I have been trying to load a OCX file into one of my VB6 projects for most of the day today. I've tried checking the COM registration in the registry the best that I know how, and have attempted several times using REGSVR32 on the file to no avail. All I keep getting from VB6 when I try to load the component (Under Project --> Components) is 'FilePath\FileName.ocx' could not be loaded. Has anyone else seen this before, and if so, any ideas how to fix it?
Just a couple of tips to help isolate the problem....
Look at the control with OleView
Examine the name: if it is one of the reserved words such as 'Menu', vb6 will fail to load it. (Although vb6 will happily let you create (and use) one with a bad name until it is saved and reloaded)
Examine the interface: does it describe the functionality? You may have a damaged or unlicensed ocx.
Attempt to load it with the ActiveX Control Test Container...
If you can, the problem is with VB6 and not the ocx.
This it may be a dependency issue -- some other component needed by the OCX is not present. Dependency Walker will find any static dependencies.
We fixed similar error recently. In our case the error was in the Visual Basic project (.vbp) file. Project file had been edited outside standardized build machine and contained references to OCX components - including workstation specific paths & versions of the components.
You can either edit the the project file in text editor or get a working version from version control.
Un-registering and registering again worked for me too.
Please note that you need to register this component using this syntax:
regsvr32 /i:design olch2x8.ocx
When you say you have used "REGSVR32 on the file to no avail" do you mean that you get a file name succeeded message, or an error message? If registering the file succeeds CMB is likely right about the ocx being unlicensed.
Licensing aside, there are a couple of other trip points with vb6. Especially if the OCX was developed in VB6.
If so, the 'officially' system registered version may conflict with the specific ocx you're using. In other words, both of them might have the same proper name (or classid) but the one you're attempting to use may not implement all the functionality described in the system registered one (i.e. you have a less evolved version). This arises when the author desires to maintain binary compatibility while enhancing the functionality of a control. As long as the public interfaces remain compatible, vb will not recalculate the classid.
You can fix this by forcibly unregistering the specific control (actually unregister all instances of the control). (regsvr32 /u control.ocx ) Then re-register the one you intend to use. Be certain that no running instance of VB6 exists when you do this or the results might not work. (Check your task list)
Hope that helps...
The control may be reliant on another DLL or OCX that may be missing or not registered and this could manifest itself as VB reporting that the control you're trying to use is missing. However, I'm not sure how you would identify the dependencies. As far as I know, dependency walker identifies static dependencies; I'm not sure if it can identify COM dependencies.
Un register the Ocx
re register the ocx
then loaded the project again in VB6, it worked for me.
Thanks everyone